Is a guy with power like Cespedes someone to be careful with? Iwakuma immediately answered, “Hai.”

That’s yes in Japanese.

Iwakuma was not careful enough in the Mariners’ 6-3 loss Friday night to the A’s. Cespedes’ two-run homer in the first inning started a four-homer night for the A’s and jettisoned the Mariners to 32-43, a season-high 11 games under .500.

Iwakuma (7-3) typically relies on the rapid drop of a split-finger fastball as his wipeout pitch. Often Friday, that pitch stayed level. All three home runs he allowed were on split-finger pitches.

Meanwhile, the Mariners did themselves few favors against Bartolo Colon (10-2), who also beat them last Sunday.

In the sixth inning, Kyle Seager led-off with a single. He moved to second on a passed ball before deciding to try for third. He was easily thrown out. Instead of having the tying run on second base with no outs, the Mariners had no one on and one out following the improper decision.

“Can’t happen,” Mariners manager Eric Wedge said.

Kendrys Morales followed with an infield single. Raul Ibanez walked on four pitches. However, Justin Smoak and Mike Zunino couldn’t move either along.

That’s not surprising. Colon has been stingy. Nick Franklin’s three-run home run in the third inning was the first homer the veteran had allowed in 48 innings. It was the first time Colon had allowed three earned runs in a game since May 14.

It was also the first homer that Franklin, a rookie, has hit at Safeco Field and his fourth home run this year.

Franklin’s home run was a rubber mallet to Cespedes’ stone hammer. Cespedes’ rocket-fueled two-run homer in the first inning hit the facade of the second deck. It was estimated at 431 feet.

Oakland shortstop Jed Lowrie knocked out a solo homer in the fourth. Coco Crisp hit one in the sixth. It was the first time this season Iwakuma had allowed three home runs in a game. It was also the first time Iwakuma had allowed multiple homers in his 18 career starts at Safeco. He threw seven innings, struck out six and all four earned runs came from homers.

“He’s been up a little bit more,” Wedge said of Iwakuma. “I’ve been talking about the quality of his misses a lot this year, and he’s just been a tad off on that.”

Cespedes wasn’t done when Iwakuma was. He turned what was a tight game most of the night into a convenient three-run lead when he hammered a two-run homer to left field off Tom Wilhelmsen in the top of the ninth.

Wilhelmsen is trying to reassemble his season. After a dominating first two months, June has been a disaster for the former closer. He allowed a leadoff single before Cespedes powered an 0-1 pitch for his 15th homer of the year.

Wilhelmsen has allowed at least a run in six of his nine June appearances. After giving up two earned runs in the first two months of the season, Wilhelmsen has been knocked around for 13 in June.